We believe that central catecholamine-containing neurons may mediate the cognitive and locomotor components of arousal that are fundamental properties of motivated behavior and characteristic manifestations of higher mental activity. Because of the unique function of central catecholaminergic pathways that we perceive, we expect that following experimental lesions compensations will occur within the damaged system (as in the autonomic nervous system) and thereby provide the basis for the observed recovery of function. Our research will focus on the adaptive changes that occur following damage to the dopaminergic fibers of the nigrostriatal bundle, and the dorsal bundle of noradrenergic neurons. We will relate activity in these prominent catecholaminergic projections to feeding and drinking behaviors, but our findings should extend to more general considerations of motivated behaviors. In short, we will be studying the regulation of synaptic transmission in central fiber systems and their significance to animal behavior, and our data should permit insights into the workings of these systems in intact and brain-damaged animals as well as provide an outline of aspects of the central control of motivated behavior. Given the importance of the fiber systems that we will be studying, our research, while of a rather basic nature, should also have considerable significance for problems related to mental health and cerebral dysfunctions, including Parkinson's disease, mental retardation, and drug tolerance.